Tanker ventilating and drying system



Oct. 20, 1959 DEHUMIDIFIER STEAM TURBINE INVENTOR VIGGO KRISTOFFERSEN HIS ATIORNEXS United States Patent TANKER VENTILATING AND DRYING SYSTEM Viggo Kristoflersen, Jackson Heights, N.Y., assignor to Gotaas-Larsen, Inc., New York, N.Y., a corporation of New York Application January 14, 15 58, Serial No. 708,865

8 Claims. (Cl. 98-39) This invent-ion relates to ventilating systems for the compartments of tank vessels and, more particularly,-to a new and improved system accomplishing tanker ventilation rapidly with maximum efficiency.

After the removal of a cargo of oil or the like from the compartment of a tanker, a residue remains within the compartment which must be eliminated before the compartment can be filled with a different cargo. Associated with this residue, a vapor, which is frequently asphyxiating or explosive, fills the compartment preventing entry therein for cleaning or other purposes.

In order to remove the residue and associated vapor, tanker compartments are customarily cleaned from without by suction applied to the filling lines or to a separate duct inserted in the compartment, application of air under pressure to the hatch having been found inefficient because of the inadequate circulation obtained thereby.

Also, warmair containing water vapor is cooled upon entering the tanks which are kept at a lower temperature by the surrounding water, o ften causing the vapor to condense and be deposited in the form of moisture on the inside surfaces of the compartment, stimulating corrosion of these surfaces. In addition, the rate of corrosion is further increased by moisture remaining within the compartment after it has been washed down to remove residue not evacuated by the suction.

Accordingly, it is an object of this invention to provide a new andimproved system for ventilating the compartments of a tank vessel.

Another object of the invention is to provide a system of the above character wherein corrosion of the compartment surfaces is substantially reduced.

A further object of the invention is to provide a new and improved method and means for eliminating vapors from tanker compartments without depositing moisture therein by condensation. 1

These and other objects of the invention'are attained by providing an air line connected to the filling line for each compartment and supplying air thereto under substantial pressure .therebyforcing the vapors within the filling line and the compartment outthrough the compartment hatch, the accessible outlet of the filling line being sealed. In one embodiment of the invention, air pressure is obtained by a blower powered from a steam turbine and the turbineexhaust isdirected to a heater arranged to preheat the air, thus increasing its vapor capacity. Additionally, a dehumidifier may be inserted in the air supply line to further increase its capacity for vapors and moisture. v

.fFurther objects and advantages of the invention will be readily apparent from a reading of the following desc'r-iption inxconjunctionwith thesingle accompanying drawingwhichis .a partial longitudinal 1 section of ata nker ilustrating, schematically, ,a ventilating system arranged according to the'inve ntion. p

Referring to the drawing,- the tanker is divided into several compartments 10, only three of which are illustrated, by a series of lateral bulk heads 11, each of the ICC 2 compartments being accessible from the top deck 12 through a hatch 13. Each batch is normally closed by a hatch cover 14 having the customary air passages arranged to permit displacement of air to and from the compartments during filling and emptying.

Liquid cargo is supplied to and removed from each compartment through a filling pipe 15 which may, for example, be of fourteen inch diameter, leading to a discharge pipe 16 provided with a downwardly directed nozzle 17 positioned just above the bottom of the compartment and leaving a minimum space 18 therebetween so that substantially all of the cargo within the compartment can be withdrawn through the filling pipe 15. Any liquid lying at a level below the nozzle within the space 18, however, cannot be withdrawn in this manner and thus a residue remains at the bottom of the compartment as well as in the pipe 15 after the compartment has been emptied.

It will be understood that each filling pipe 15 may be connected to more than one discharge pipe 16 so that liquid cargo can be supplied to or removed from a number of compartments simultaneously. In order to control the flow of liquid to or from a single selected compartment, a valve 16a is interposed between 'each pipe 16 and the associated filling pipe 15, a reach rod 16b extending from the valve to the top deck of the tanker to permit operation from that location.

Inasmuch as further suction applied to the pipe 15 'after the liquid cargo has been removed in the above manner merely draws air in through the hatch 13 and over the surface of the residue to the nozzle 17 without substantially moving the liquid or disturbing its surface, vaporization and removal of the residue in this manner constitutes a slow and inefficient process. In order to agitate the liquid and thereby promote rapid vaporization thereof and increased air circulation throughout the compartment 10 to gather the vapors and carry them out "through the hatch 13, air must be directed at the residue under substantial pressure.

To this end, a ventilating system is arranged according to the invention with filling pipe 15, a valve 20 is provided therein, each of the pipes 19 being connected through a valve 21 to the 'outlet of aconventional blower 22 which receives fresh air through a ventilator cowl 23.

The blower 22, which may be of the centrifugal type,

is preferably driven by a steam turbine 24 and has suflicient capacity to supply eight thousand cubic feet of air per minute at eighteen inches water gauge pressure. If

desired, a totally enclosed or explosion proof electric motor, for example, may be substituted for the steam turbine. Thus, four thousand cubic feet per minute can be supplied to two compartments simultaneously at -a pressure sufficient to induce maximum agitation of the 'residue in the spaces 18 for most liquids, the pressure required being dependent upon the physical characteristics of the liquid forming the residue.

With a volume of four thousand cubic feet per minute a minimum air velocity of about four thousand feet per minute is obtalnable at a nozzle providing an outlet area into the compartment of about one square foot which is approximately the maximum area for conventional tanker nozzles and this velocity is sufiicient to agitate even the heaviest liquid normally carried by a tanker so that it is atomized. With a nozzle providing a smaller outlet area,

the air velocity produced when air is supplied at four thousand cubic feet per minute may. be as high as eleven thousand feet per minute while if air is supplied to a nozzle of this size at eight thousand cubic feet per minute, as described above, the outlet velocity can be as high as twenty-two thousand feet per minute. Steam power is supplied to the turbine 24 through a line 25 and, if desired, the hot exhaust gases therefrom may be utilized to heat the intake air by passing them through a line 26 to a conventional heat exchanger 27, which preheats the incoming air from the cowl 23 inorder to in crease its vapor capacity. In addition, a dehumidifier 28 may be included in the air supply line to remove moisture or other vapors from the intake air, further increasing its ability to remove vapors from the compartments 10.

In operation, after a liquid cargo has. been removed from a compartment or after the compartment has been washed down, leaving a liquid residue, the valye20 is closed and the corresponding valve 21 is opened, permitting lfresh air from the cowl 23, preheated by the heater 27 and compressed by the blower 22, to be driven through the pipe 19 to the filling pipe absorbing the residual vapors therein. Passing through the nozzle 17 under high pressure, the air is directed at the residue in the space 18 agitating it greatly to promote vaporization and collecting the vapors therefrom and from the interior of the compartment to carry them out through the hatch 13. If desired, in climates or conditions where the vapor content of the air is high, the residual moisture may be removed by reheating or dehumidification thus preventing any condensation within the compartment. Accordingly, the ventilating system of the present invention not only provides maximum agitation to vaporize the residue, but also is capable of supplying air of higher vapor capacity than other systems, thereby drying tanker compartments more rapidly and with greater efilciency.

Further, the unique arrangement of the ventilating system described herein is peculiarly adapted to the rapid removal of vapors from the filling pipes 15 inasmuch as fresh air under compression is passed through them on its way to the compartments 10. Thus, if it is necessary to clear one of the filling pipes for repair work, for example, the valve 16a may be closed and the valve 20 opened to permit air from the blower 22 to evaporate liquids remaining in the upper portion of the pipe. Closing of the valve 20 and opening of the valve 16a allows air to be blown to the lower portion of the pipe 15 as long as is necessary to completely remove vapors therefrom after which the valve 16a is closed again. In this manner, each of the filling pipes may be cleared completely of vapors without removing the entire residue from any of the compartments 10.

Although the invention has been described herein with reference to a specific embodiment, many modifications and variations therein will occur to those skilled in the art. Accordingly, the invention is not intended to be restricted in scope except as defined by the following claims.

I claim:

1. Apparatus for ventilating and drying a tanker compartment which is open to the atmosphere and which cannot be drained completely comprising a pipe extending to the bottom of the compartment, a nozzle very closely adjaccnt'to and directed toward the bottom of the compartment and connected to the pipe, and a blower supplying air under substantial pressure to the pipe to direct it through the nozzle against the bottom of the compartment so that the air escapes from the nozzle with a velocity within the range from four thousand to twenty-two thousand feet per minute inclusive, thereby atomizing any layer of liquid lying at the bottom of the compartment. 1

2. Apparatus according to claim 1 including a heater arranged to heat the air supplied by the blower.

3. Apparatus according toclaim 1 including means for dehumidifying the air supported by the blower.

fit

4. Apparatus for emptying, ventilating and drying at p tanker compartment-which is open to the atmosphere and which cannot be drained completely comprising a filling pipe extending to the bottom of the compartment through which the compartment can be filled and emptied and air can be introduced, a nozzle through which liquid cargo can be withdrawn very closely adjacent to and directed toward the bottom of the compartment and connected to the filling pipe, a blower" for supplying air under substantial pressure to the filling pipe to direct it through the nozzle against the bottom of the compartment so that air escapes from the nozzle with a velocity within the range from four thousand to twenty-two thousand feet per minute inclusive, thereby atomizing any layer of liquidlying at the bottom of the compartment, a filling and emptying opening at the upper end of the filling pipe, and a valve at the opening adapted to be opened to permit liquid to be introduced into or withdrawn from the compartment through the pipe and to be closed to prevent air from escaping through the opening when the blower supplies air to the filling pipe.

5. A method for ventilating and drying a tanker compartment having an upper portion open to the atmosphere and a pipe extending to the bottom of the compartment and a nozzle very closely adjacent to and directed toward the bottom of the compartment and connected to the pipe, said method comprising the steps of blowing air under substantial pressure through the pipe, directing the air through the nozzle and releasing it against the bottom surface of the compartment very closely adjacent thereto so that air escapes from the nozzle with a velocity within the range from four thousand to twenty-two thousand feet per minute inclusive thereby agitating any layer of liquid lying at the bottom of the compartment, to atomize and vaporize it, and driving out the resulting mixture of air, fluid particles, and vapor through the upper portion of the compartment.

6. A method according to claim 5 including the step of dehumidifying the air before blowing it through the p1pe.

7. A method according to claim 5 including the step of heating the air before blowing it through the pipe.

8. A method for emptying, ventilating, and drying a tanker compartment having an upper portion open to the atmosphere and apipe extending to the bottom of the compartment and a nozzle connected to the pipe very closely adjacent to and directed toward the bottom of the compartment said method comprising the steps of withdrawing liquid through the nozzle by suction until the liquid level is below that of the nozzle, then agitating the remaining liquid to atomize and vaporize it by supplying air under substantial pressure through the pipe to thenozzle so that air escapes from the nozzle with a velocity of at least four thousand feet per minute, and driving out the resulting mixture of air, fluid particles, and vapor through the upper portion of the compartment.

References Cited in the file of this patent 

